Catalytic behaviors of supported cu, ni, and co phosphide catalysts for deoxygenation of oleic acid

Abstract

Catalytic behaviors of copper phosphide supported on various oxides (SiO2, γ-Al2O3, and USY zeolite) have been evaluated for deoxygenation of oleic acid and compared with nickel and cobalt phosphides. All catalysts were prepared by the hydrogen reduction of metal phosphate precursors. CoP and Ni2P were obtained on USY zeolite, while Cu3P was formed on USY and SiO2 supports. On the contrary, the metallic Cu phase was stabilized on γ-Al2O3 support. Metal phosphide particles were highly dispersed on the USY support. Cu3P/USY exhibited much larger surface area and higher acidity compared to Cu3P/SiO2, owing to the textural and acidic properties of the USY zeolite support. All supported catalysts gave an oleic acid conversion close to 100% at 340 °C. Ni2P/USY, CoP/USY, and Cu/γ-Al2O3 favored the deoxygenation of oleic acid to alkane products such as heptadecane and octadecane. Highly selective production of octadecane (98%) through hydrodeoxygenation pathway occurred on Cu/γ-Al2O3. In contrast, the supported Cu3P catalysts favored cyclization and aromatization to form cyclic and aromatic compounds such as dodecylcyclohexane, heptylcyclopentane, and dodecylbenzene. Cu3P/SiO2 provided dodecylbenzene in higher yield (46%) than Cu3P/USY (33%).